The variation in tuber mineral concentrations amongst accessions of wild tuber-bearing Solanum species in the Commonwealth Potato Collection (CPC) was evaluated under greenhouse conditions. Selected CPC accessions, representing the eco-geographical distribution of wild potatoes, were grown to maturity in peat-based compost under controlled conditions. Tubers from five plants of each accession were harvested, bulked and their mineral composition analysed. Among the germplasm investigated, there was a greater range in tuber concentrations of some elements of nutritional significance to both plants and animals, such as Ca, Fe and Zn (6.7-fold, 3.6-fold, and 4.5-fold, respectively) than others, such as K, P and S (all less than threefold). Significant positive correlations were found between mean altitude of the species' range and tuber P, K, Cu and Mg concentrations. The amount of diversity observed in the CPC collection indicates the existence of wide differences in tuber mineral accumulation among different potato accessions. This might be useful in breeding for nutritional improvement of potato tubers.

The variation in tuber mineral concentrations amongst accessions of wild tuber-bearing Solanum species in the Commonwealth Potato Collection (CPC) was evaluated under greenhouse conditions. Selected CPC accessions, representing the eco-geographical distribution of wild potatoes, were grown to maturity in peat-based compost under controlled conditions. Tubers from five plants of each accession were harvested, bulked and their mineral composition analysed. Among the germplasm investigated, there was a greater range in tuber concentrations of some elements of nutritional significance to both plants and animals, such as (Ca, Fe and Zn; 6.7, 3.6, and 4.5-fold respectively) than others, such as (K, P and S; all <3-fold). Significant positive correlations were found between mean altitude of the species' range and tuber P, K, Cu and Mg concentrations. The amount of diversity observed in the CPC collection indicates the existence of wide differences in tuber mineral accumulation among different potato accessions. This might be useful in breeding for nutritional improvement of potato tubers. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation 1 Genetic Variation for Tuber Mineral Concentrations in Accessions of the Commonwealth Potato Collection Nithya K. Subramanian, Philip J. White, Martin R. Broadley and Gavin Ramsay N. K. Subramanian, G. Ramsay Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK Email: nithya@tamu.edu; Telephone: 979-845-6498. P. J. White Ecological Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK and Distinguished Scientist Fellowship Program, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia N. K. Subramanian, M. R. Broadley Division of Plant and Crop Sciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, LE12 5RD, UK Present Address: N. K. Subramanian Department of Soil and Crop Sciences, Texas A&M University, College Station, Texas-77843, USA.

Potatoes are a globally important source of food whose production requires large inputs of fertiliser and water. Recent research has highlighted the importance of the root system in acquiring resources. Here measurements, previously generated by field phenotyping, tested the effect of root size on maintenance of yield under drought (drought tolerance).

Genome-wide QTL analysis of potato tuber carotenoid content was investigated in populations of Solanum tuberosum Group Phureja that segregate for flesh colour, revealing a novel major QTL on chromosome 9.

1The James Hutton Institute, Invergowrie, Dundee DD2 5DA 2The Game and Wildlife Conservation Trust, Fordingbridge, Hampshire SP6 1EF 3Stockbridge Technology Centre, Cawood, Selby North Yorkshire YO8 3TZ 4Permaculture Association, BCM Permaculture Association, London WC1N 3XX 5Organic Research Centre, Hamstead Marshall, Newbury RG20 0HR 6Division of Plant Sciences, Dundee University 7Scotlands Rural College, Edinburgh EH9 3JG Corresponding Author Email: Pete.Iannetta@hutton.ac.uk

Aims Potatoes have an inadequate rooting system for efficient acquisition of water and minerals and use disproportionate amounts of irrigation and fertilizer. This research determines whether significant variation in rooting characteristics of potato exists, which characters correlate with final yield and whether a simple screen for rooting traits could be developed. Methods Twenty-eight genotypes of Solanum tuberosum groups Tuberosum and Phureja were grown in the field; eight replicate blocks to final harvest, while entire root systems were excavated from four blocks. Root classes were categorised and measured. The same measurements were made on these genotypes in the glasshouse, 2 weeks post emergence. Results In the field, total root length varied from 40 m to 112 m per plant. Final yield was correlated negatively with basal root specific root length and weakly but positively with total root weight. Solanum tuberosum group Phureja genotypes had more numerous roots and proportionally more basal than stolon roots compared with Solanum tuberosum , group Tuberosum genotypes. There were significant correlations between glasshouse and field measurements. Conclusions Our data demonstrate that variability in rooting traits amongst commercially available potato genotypes exists and a robust glasshouse screen has been developed. By measuring potato roots as described in this study, it is now possible to assess rooting traits of large populations of potato genotypes.

The green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae), damages potato worldwide. In this study, we investigated 21 Commonwealth Potato Collection (CPC) accessions from seven wild Solanum species in order to identify sources of resistance against the green peach aphid. Test plants of wild potato species were grown from seed. After 4 weeks, 5 wingless adult aphids were put onto each test plant. The number of aphids was counted after 24 h, 7 and 10 days. At the second screening stage, plants were tested after 4 week's growth, using the same aphid bioassay as in the first stage screen. Results showed that the most resistant Solanum species to M. persicae were S. trifidum and S. palustre and the most susceptible species tested was S. sanctae-rosae. Stability of the detected aphid resistance during plant development was measured by the correlation of repeated tests S. jamesii (CPC 7166) and S. trifidum (CPC 7123) were significantly more correlated than other accessions tested. The number of glandular hairs on these two resistant species was low and medium respectively. Therefore, resistance of these CPC accessions does not appear to depend on the presence of glandular hairs. Based on glasshouse tests, these two CPC accessions may be useful for novel aphid resistance traits in potato to M. persicae.

Summary Worldwide, many people are zinc (Zn)-deficient. Dietary Zn intake can be increased by producing crops with higher concentrations of Zn in their edible portions. This can be achieved by applying Zn-fertilisers to varieties with an increased ability to acquire Zn and to accumulate Zn in their edible portions. Potato (Solanum tuberosum L.) is an important food crop and is, therefore, a target for bio-fortification with Zn. Field trials incorporating a core collection of 23 potato genotypes, performed over 4 years (2006 – 2009), indicated significant genotypic effects on tuber Zn concentration and suggested that tuber Zn concentration was influenced by environmental effects, but also found that genotype × environment (G × E) interactions were not significant. Tuber Zn concentrations averaged 10.8 mg kg–1 dry matter (DM), and the ratio between the lowest and the highest varietal tuber Zn-concentration averaged 1.76. Tuber Zn concentrations could be increased by foliar Zn-fertilisation. Tuber yields of ‘Maris Piper’ were unaffected by foliar applications of < 1.08 g Zn plant–1. The relationship between tuber Zn concentration and foliar Zn application followed a saturation curve, reaching a maximum at approx. 30 mg Zn kg–1 DM at a foliar Zn application rate of 1.08 g plant–1. Despite a 40-fold increase in shoot Zn concentration compared to the unfertilised controls following foliar Zn-fertilisation with 2.16 g Zn plant–1, only a doubling in tuber Zn concentration was observed. This suggests that the bio-fortification of tubers with Zn was restricted by the limited mobility of Zn in the phloem. A significant positive linear relationship between tuber Zn concentration and tuber N concentration supported the hypothesis of co-transport of Zn and N-compounds in the phloem.

BACKGROUND AND AIMS The three-dimensional distributions of mineral elements in potato tubers provide insight into their mechanisms of transport and deposition. Many of these minerals are essential to a healthy human diet, and characterizing their distribution within the potato tuber will guide the effective utilization of this staple foodstuff. METHODS The variation in mineral composition within the tuber was determined in three dimensions, after determining the orientation of the harvested tuber in the soil. The freeze-dried tuber samples were analysed for minerals using inductively coupled plasma-mass spectrometry (ICP-MS). Minerals measured included those of nutritional significance to the plant and to human consumers, such as iron, zinc, copper, calcium, magnesium, manganese, phosphorus, potassium and sulphur. KEY RESULTS The concentrations of most minerals were higher in the skin than in the flesh of tubers. The potato skin contained about 17 % of total tuber zinc, 34 % of calcium and 55 % of iron. On a fresh weight basis, most minerals were higher in tuber flesh at the stem end than the bud end of the tuber. Potassium, however, displayed a gradient in the opposite direction. The concentrations of phosphorus, copper and calcium decreased from the periphery towards the centre of the tuber. CONCLUSIONS The distribution of minerals varies greatly within the potato tuber. Low concentrations of some minerals relative to those in leaves may be due to their low mobility in phloem, whereas high concentrations in the skin may reflect direct uptake from the soil across the periderm. In tuber flesh, different minerals show distinct patterns of distribution in the tuber, several being consistent with phloem unloading in the tuber and limited onward movement. These findings have implications both for understanding directed transport of minerals in plants to stem-derived storage organs and for the dietary implications of different food preparation methods for potato tubers.

The factors that regulate storage organ carotenoid content remain to be fully elucidated, despite the nutritional and economic importance of this class of compound. Recent findings suggest that carotenoid pool size is determined, at least in part, by the activity of carotenoid cleavage dioxygenases. The aim of this study was to investigate whether Carotenoid Cleavage Dioxygenase4 (CCD4) activity affects potato (Solanum tuberosum) tuber carotenoid content. Microarray analysis revealed elevated expression of the potato CCD4 gene in mature tubers from white-fleshed cultivars compared with higher carotenoid yellow-fleshed tubers. The expression level of the potato CCD4 gene was down-regulated using an RNA interference (RNAi) approach in stable transgenic lines. Down-regulation in tubers resulted in an increased carotenoid content, 2- to 5-fold higher than in control plants. The increase in carotenoid content was mainly due to elevated violaxanthin content, implying that this carotenoid may act as the in vivo substrate. Although transcript level was also reduced in plant organs other than tubers, such as leaves, stems, and roots , there was no change in carotenoid content in these organs. However, carotenoid levels were elevated in flower petals from RNAi lines. As well as changes in tuber carotenoid content, tubers from RNAi lines exhibited phenotypes such as heat sprouting, formation of chain tubers, and an elongated shape. These results suggest that the product of the CCD4 reaction may be an important factor in tuber heat responses.

There is concern that modern cultivars and/or agronomic practices have resulted in reduced concentrations of mineral elements essential to human nutrition in edible crops. Increased yields are often associated with reduced concentrations of mineral elements in produce, and a number of recent studies have indicated that, when grown under identical conditions, the concentrations of several mineral elements are lower in genotypes yielding more grain or shoot biomass than in older, lower-yielding genotypes. Potato is a significant crop, grown worldwide, yet few studies have investigated whether increasing yields, through agronomy or breeding, affects the concentrations of mineral elements in tubers. This article examines the hypothesis that increasing yields, either by the application of mineral fertilizers and/or by growing higher-yielding varieties, leads to decreased concentrations of mineral elements in tubers. It reports that the application of fertilizers influences tuber elemental composition in a complex manner, presumably as a consequence of soil chemistry and interactions between mineral elements within the plant, that considerable variation exists between potato genotypes in the concentrations of mineral elements in their tubers, and that, like in other crops, higher-yielding genotypes occasionally have lower concentrations of some mineral elements in their edible tissues than lower-yielding genotypes.

Phytochemical diversity was examined by gas chromatography-mass spectrometry in tubers of genotypes belonging to groups Andigena, Phureja, Stenotomum, and Tuberosum of the potato, Solanum tuberosum. Polar extracts (mainly amino acids, organic acids, sugars, and sugar alcohols) and nonpolar extracts (mainly fatty acids, fatty alcohols, and sterols) were examined. There was a large range in levels of metabolites, including those such as asparagine, fructose, and glucose, that are important to tuber quality, offering considerable scope for selecting germplasm for breeding programmes. There were significant differences in the levels of many metabolites among the groups. The metabolite profiles of genotypes belonging to Phureja and Stenotomum were similar and different from those of Tuberosum and the majority of Andigena genotypes. There was some agreement with the phylogeny of the groups in that Stenotomum is believed to be the ancestor of Phureja and they are both distinct from Tuberosum. Andigena genotypes could be partially distinguished according to geographical origin, Bolivian genotypes being particularly distinct from those from Ecuador. Biosynthetic links between metabolites were explored by performing pairwise correlations of all metabolites. The significance of some expected and unexpected strong correlations between many amino acids (e.g., between isoleucine, lysine, valine, and other amino acids) and between several nonpolar metabolites (e.g., between many fatty acids) is discussed. For polar metabolites, correlation analysis gave essentially similar results irrespective of whether the whole data set, only Andigena genotypes, or only Phureja genotypes were used. In contrast, for the nonpolar metabolites, Andigena only and Phureja only data sets resulted in weaker and stronger correlations, respectively, compared to the whole data set, and may suggest differences in the biochemistry of the two groups, although the interpretation should be viewed with some caution.

Biological Environmental Science aims to be an introductory textbook for undergraduate students in environmental science. The book covers quite a range of areas, mainly various forms of pollution, but also global warming, biodiversity, population growth and environmental law. A strong point of the book is its extensive collections of references. In the preface the author claims that ‘the book utilizes the original research literature’. This is a rather fitting description, since it provides very little added value to this collection of references. In large parts the book reads as if the author had abstracted parts of the research literature, as well as applicable websites. Unfortunately these abstracts were not then connected into a coherent text. Basically the reader needs to consult the original literature in order to get any information. The chapter on global warming, for example, contains a section on the effects of CO2 and climate change on biological organisms. This section consists of four paragraphs listing references where the reader could find information on these, while lacking a detailed discussion of the actual effects. The reader therefore needs to consult the original literature in order to actually get the information one would expect from an undergraduate textbook. I therefore feel unable to recommend the book in any way.

Scottish wild red raspberry ( Rubus idaeus ) plants at 12 sites were re-examined 10 years after initial studies had been carried out to examine the decline in population size and to address an earlier finding that demonstrated significant population differentiation over a small scale. Ten simple sequence repeat (SSR) loci were screened on the plants and a total of 80 alleles were detected, half of which were unique to a particular population, with all populations containing unique SSR alleles. Only 18 of the 80 alleles present in the wild were found in cultivated raspberries, highlighting the genetic diversity available for future breeding. This finding makes the decline in population number observed a concern, as this unique diversity is being eroded, primarily due to human impact. An additional 17 unique alleles were identified in the cultivars that were not present in the wild individuals studied. Gene flow into one lowland site was identified by the gain of one new allele into progeny at the site, but three alleles were also lost from parents to progeny. SSR markers were used to estimate the levels of outcrossing in wild red raspberry for the first time, and confirmed that the populations studied were outcrossing, intermating populations. The nonsignificant global F IS value indicates that red raspberry is an outbreeder (global F IS = −0.117), but significant population differentiation was observed [global F ST = 0.348 ( P < 0.001)]. Diversity in this crop's wild relative and the population differentiation observed may have use in the future for breeding aimed at addressing climate change scenarios, and consideration should be given to means of conserving the diversity revealed by these studies.

Phytochemical diversity with respect to a range of polar (including amino acids, organic acids, sugars, and sugar alcohols) and nonpolar (including fatty acids, alkanols, and sterols) metabolites was examined within tubers from a total of 29 genetically diverse potato cultivars and Chilean landraces using a metabolomics approach by gas chromatography-mass spectrometry. From principal component analysis of the polar and nonpolar metabolite data there was insufficient variation to differentiate the majority of cultivars and landraces. Analysis of all polar metabolite profiles revealed separation of two cultivars (Glenna and Morag) from the other cultivars and landraces and a separate cluster of one landrace line, largely due to higher levels of sugars. Pentland Javelin was distinct in containing high levels of many amino acids. The two Solanum tuberosum group phureja cultivars (Inca Sun and Mayan Gold) were not particularly similar and were not separated from the S. tuberosum group tuberosum cultivars. Analysis of the nonpolar metabolite data revealed partial separation of two landrace lines and, on the basis of some minor fatty acids, Mayan Gold was distinct. The differences in metabolite profiles are considered in terms of the taxonomy and breeding history of the cultivars and possible influences from other factors such as developmental stage of the tuber. With a view to exploring biosynthetic links between metabolites, a pairwise correlation analysis was performed on all metabolites. The significance of high correlations between many amino acids and between several nonpolar metabolites is discussed.

BACKGROUND: High erucic acid oilseed rape (HEAR) was tested as a source crop for estimates of regional geneflow. Two methods to detect HEAR in low erucic acid oilseed rape (LEAR) were compared: real-time quantitative PCR (qPCR) and gas chromatography (GC).RESULTS: Fields (2.5 ha) of a LEAR variety (0.028% EA) in Tayside and Hertfordshire were juxtaposed adjacent to and I km distant from a HEAR (44% EA) field. The LEAR variety was a varietal association to ensure high cross-pollination (CP). The methods were highly correlated, measuring between 30% and 0.5% CP. However, the qPCR method became unreliable below 0.5% CP, whereas GC was robust enough to detect raised EA equivalent to one F1 seed in 500 (0.2%). A statistical mixture model was fitted to the distributions of EA in samples in order to assign a CP value to each 500-seed sample. Declines of CP from 30% to < 1%, and EA from 5% to 0.2%, with distance up to 150 m in the near fields was best fitted with a power function. The combined mean EA for both far fields was 0.11%, well above the background LEAR value of 0.028%, and mean CP was 0.36%.CONCLUSIONS: The GC method of detection raised %EA should be a reliable and high-throughput means of estimating %CP between fields, provided the %EA of single F1 seed in receptor fields is measured to confirm the presence of F1 seed. (c) 2008 Society of Chemical Industry.